Light-developable direct print silver halide emulsion sensitized with a combination of copper lead bromide and thiourea

ABSTRACT

A direct print light-developable photosensitive silver halide emulsion sensitized by copper, lead, bromide and thiourea. The sensitizer may be mixed with the silver halide layer forming a single-layer emulsion or may comprise a separate layer overcoating the silver halide layer forming a two-layer emulsion.

United States Patent Ivar T. Krohn;

Geoffrey A. Page; Thomas L. Mahalek, all of Rochester, N.Y.

Aug. 2, 1968 Oct. 26, 1971 Xerox Corporation Rochester, N.Y.

Continuation-impart of application Ser. No. 514,450, Dec. 17, 1965, now abandoned Continuation-impart of application Ser. No. 533,853, Mar. 14, 1966, now abandoned.

[72] Inventors [21 Appl. No. [22] Filed [45] Patented [73] Assignee 52 u.s.c| 96/108 51 Int.Cl G03cl/28 [50] Field of Search ..96/108, 107

[56] References Cited UNITED STATES PATENTS 3,033,682 5/1962 Hunt 96/108 3,123,474 10/1960 96/108 3,178,292 4/1965 96/108 3,178,293 4/1965 96/108 3,183,088 5/1965 96/45.2 3,436,221 4/1969 96/114.7

Primary Examiner-Norman G. Torchin Assistant Examiner- Richard E. Fichter Attorneys-James J. Ralabate, David C. Petre and Richard A.

Tomlin ABSTRACT: A direct print light-deveiopable photosensitive silver halide emulsion sensitized by copper, lead, bromide and thiourea. The sensitizer may be mixed with the silver halide layer forming a single-layer emulsion or may comprise a separate layer overcoating the silver halide layer forming a two-layer emulsion.

IPATENTEDHEI 26 Ian E 3,615,614

2 "SENSITIZING COATING I -NTORQ IVA KROHN GEOFFREY A. PAGE BY THOMAS L.MAHALEK Mam ATTORNEY plications Ser. No. 514,450 filed Dec. 17, 1965 now abandoned and Ser. No. 533,853 filed Mar. 14, 1966 now abancloned.

BACKGROUND OF THE INVENTION This invention relates in general to photographic emulsions. More specifically, the invention relates to photographic emulsions of the direct print light-developable type.

The term printout light-developable" refers to those photosensitive materials upon which a visible image is obtained after an initial exposure to high-intensity light or other electromagnetic radiation has been utilized to form a latent image, the visible image being obtained by an additional exposure to electromagnetic radiation. This additional exposure is known as latensification." The entire photosensitive surface is exposed, including exposure of the background area and reexposure of the area upon which the initial image was formed. Direct print light-developable materials are distinguished from developing-out emulsions in that they do not require a wet development treatment, such as a chemical development after initial exposure, to produce a visible image. While the direct print light-developable materials of this invention may be used for ordinary photographic purposes, they are particularly sensitive to a high-intensity beam of light or other electromagnetic energy and are, therefore, especially useful in high-speed recording such as osoillographic recording and the like.

Direct print light-developable materials are today in general use for recording of oscillographic traces. However, the direct print light-developable materials of the prior art are not entirely satisfactory for this recording purpose for a number of reasons. For example, it is generally true that the prior art materials which exhibit high sensitivity to an exposure of short duration to a high-intensity beam tend to exhibit a correspondingly low degree of background stability. The latensification procedure for these materials is highly critical and accordingly is exceedingly difficult to carry out. The latent image may be entirely lost during the latensification operation where the background darkens too rapidly. In other cases, a phenomena known as reversal may occur, this being a darkening of the background which proceeds at a more rapid rate than darkening of the image or trace. In these situations, the trace may be temporarily or permanently obscured. Conversely, materials which exhibit a high degree of background stability tend to exhibit a correspondingly low degree of sensitivity to the recording beam and accordingly the minimum exposure time is far above that desired for use with modern recording instruments.

Recently, attempts have been made to sensitize direct print light-developable materials in order to improve their imaging characteristics. For example, as described'by Hunt in U.S. Pat. Nos. 3,033,678 and 3,033,682 stannous or plumbous salts are added to silver halide direct print light-developable emulsions to increase their sensitivity. While the materials of the above Hunt patents show improvement in terms of higher writing speed and stability, they are not entirely satisfactory for a number of reasons. For example, although their background stability is superior to other known direct print light-developable elements and will retain a readable record over a period of several hours under the illumination of normal room lighting, background density will in time develop to a point where the image record is not sufficiently clear. The image density also has an undesirable tendency to regress. These materials also tend to be unstable to ultraviolet radiation or other radiation more intense than normal room lighting, as would be used in making by conventional methods, e.g. azo or electrophotographic copies.

Sensitized direct print light-developable materials have also been described by Byrne in US. Pat. No. 3,123,474, which describes sensitizing a silver halide emulsion with a combination of plumbous salt and thiourea. While this material shows increased sensitivity, it is not as stable when exposed for prolonged times to daylight or normal room lighting as would be desirable. Upon prolonged exposure to ordinary illumination, the background darkens and the image regresses depending upon the viewing conditions, which reduces the ratio between background and image densities.

Thus there is a continuing need for improved direct print light-developable materials having increased sensitivity and improved image and background stability when later exposed to light, during examination or storage.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide a direct print light-developable film overcoming the above-noted disadvantages.

Another object of this invention is to provide a novel lightsensitive composition.

Another object of this invention is to provide a more sensitive dry process for the reproduction of images.

Still another object of this invention is to provide a reproduction process which does not require chemical solutions for either development or fixing of the image.

Still another object of this invention is to provide an improved direct print light-developable film which possesses both a high degree of photosensitivity and a high degree of background stability upon general latensification.

A further object of this invention is to provide a direct print light-developable emulsion resistant to light degradation after imaging.

A still further object of this invention is to provide a twolayer direct print light-developable emulsion in which a sensitizing layer is coated over a photosensitive emulsion layer.

The above objects, and others, are accomplished in accordance with this invention by providing a photographic direct print light-developable film comprising photosensitive silver halide and gelatin sensitized with a combination of a soluble copper salt, a soluble lead salt, a soluble bromide salt, and a thiourea. The sensitizers may be dispersed within the silver halide and gelatin layer or the sensitizers may be dispersed in a binder and coated as a separate layer over the silver halide and gelatin layer. For the best images it is preferred to utilize the two-layer film with the silver halide overcoated with the sensitizers in a binder. For economic reasons, however, it is preferred to incorporate the sensitizers directly into the silver halide and gelatin layer.

The emulsion layer may contain any suitable conventional photosensitive silver halide.

Typical photosensitive silver halides include silver bromide, silver iodobromide, silver iodide, silver chloride, silver iodochloride, etc. Best results have been obtained with silver bromide emulsions; these are, therefore, preferred. Gelatin is the conventional binder for the photographic emulsions. However, any other suitable binder, such as polyvinyl alcohol, may be used if desired. Ordinarily, this layer should be no greater than 30 microns in thickness. For optimum results, the layer should contain about 2.5 grams of elemental silver per square meter of coated emulsion. The emulsion layer may contain additional ingredients to enhance, synergize, or otherwise modify its characteristics, as desired. Typical silver iodobromide emulsions are described in Photographic Emulsion, E. J. Wall, American Photographic Publishing Co., Boston i929).

In general the active sensitizing ingredients of this invention are used in the following amounts: (In mole percent based on the silver in the emulsion layer) about 0.03 to about 1.5 mole percent copper salt, about 0.07 to 50 mole percent lead salt, about 10 to 200 mole percent bromide and about 0.4 to 6 mole percent of a thiourea. Where the sensitizers are mixed in with the silver halide in a single layer, the active sensitizing ingredients should preferably be incorporated in the following amounts: (In mole percent based on the silver in the emulsion layer) about 0.04 to 0.5 mole percent copper salt, about 0.07 to 2 mole percent lead salt, about to 120 mole percent bromide, and about 0.2 to 2 mole percent of a thiourea.

For highest contrast, highest photosensitivity, and lowest background density, the amounts of sensitizing agents (in mole percent per mole of silver) about 0.07 to 0.17 mole percent copper salt, about 0.13 to 0.66 mole percent lead salt, about 37 to 62 mole percent bromide salt, and about 0.5 to 0.95 mole percent ofa thiourea.

Where the sensitizers are dispersed in an overcoating layer, the thickness of the overcoating should be about 0.3-0.8 times the thickness of the emulsion layer for best results. Layers of these thicknesses have been found to produce optimum sensitivity and image contrast. Where the sensitizing layer is about half the thickness of the emulsion layer, the active ingredients of the sensitizing layer should be incorporated in the following amounts: (In mole percent based on the silver in the emulsion layer) about 0.03 to 1.5 mole percent copper salt, about 1 to 50 mole percent lead salt, about 10 to 200 mole percent bromide, and about 0.4 to 6 mole percent of a thiourea.

For highest contrast, highest photosensitivity, and lowest background density, the amounts of sensitizing agents in the sensitizing layer (in mole percent per mole of silver in the emulsion layer) for a sensitizing layer half the thickness of the emulsion layer are: about 0.2 to 0.4 mole percent copper salt, about 4 to 8 mole percent lead salt, about 50 to 80 mole percent bromide salt, and about 1.5 to 3 mole percent of a thiourea. A direct-writing light-developable film having a silver halide emulsion layer overcoated with a sensitizing layer including the above-listed amounts of sensitizers has outstanding photosensitivity and stability characteristics. A highly desirable direct-writing light-developable film is produced by this overcoating configuration.

While the mechanism of sensitizing with a sensitizing layer over a photosensitive emulsion layer is not fully understood, it appears that some diffusion of sensitizing ions across the twolayer interface occurs. However, it is clear that a highly effective film is produced in the overcoated configuration, while the same ingredients are less effective when mixed directly with the photosensitive silveriodobromide emulsion. In either case the combination of the four ingredients has a synergistic effect; that is, while each ingredient alone has a slight sensitizing effect, the four used together produce an effect much greater than additive. This effect is pointed out more particularly in the examples below.

The copper and lead ions incorporated in the emulsion may be introduced in the form of any water-soluble salt thereof. Lead nitrate, lead acetate, copper sulfate, and copper nitrate have been found to be especially suitable forms. These salts are highly soluble in the coating solutions and the nitrate, acetate, and sulfate ions do not interfere with the imaging process. Any other suitable soluble salts of copper and lead may be used, if desired. The bromide ion may be introduced into the emulsion in the form of any suitable water-soluble bromide salt. Potassium bromide has been found to be especially desirable since it is highly soluble and the potassium ion does not interfere with the imaging process. Any other suitable bromide may be used, if desired.

The thiourea may be in any suitable form, substituted or unsubstituted. Best results have been obtained with diethylthiourea; this, therefore, is the preferred form.

The following examples are intended to illustrate various preferred embodiments of the direct print light-developable emulsions of this invention. All percentages used are mole percentages per mole of silver unless otherwise indicated. In the following examples, examples l-Llll are made by incorporating the sensitizers into the silver halide emulsion forming a single-layer emulsion. The remainder of the examples demonstrate the two-layer coating as shown in the FIGURE wherein the silver halide emulsion layer is overcoated with the sensitizing layer.

In examples I through Llll a silver bromide photosensitive emulsion containing the sensitizers is coated onto a paper base to a dry thickness of about 10 microns. This emulsion is prepared in a conventional manner, such as described in the above-cited publications. The emulsion contains about 2.5

grams of silver per square meter of coated emulsion. In each of the examples, the lead, copper and bromide ions are introduced into the emulsion mix in the form of lead nitrate, cupric nitrate and potassium bromide. The direct print lightdevelopable films thus produced in each example are exposed to an oscillographic trace in Model 5-124 Recording Oscillograph, available from Consolidated Electrodynamic Corporation. The overall, latensification, exposure is to General Electric Cool White Fluorescent lamps.

EXAMPLES l-IX In these examples, the quantities of lead salt, bromide and diethyl thiourea are maintained constant at 0.66 mole percent lead, 0.49 mole percent diethyl thiourea and 50 mole percent bromide. The amount of copper salt present is varied from none in example 1 through 2.3 mole percent in example 1X. As can be seen from the ratings given for the images produced, as listed in table I, no image is produced with no copper ions present. As copper salt is added, the quality of the image rises.

EXAMPLES X-XVl EXAMPLES XVII-XXIV In each of these examples, the quantities of copper salt, lead salt, and diethyl thiourea are maintained constant at 0.13 mole percent copper, 0.66 mole percent lead and 0.49 mole percent diethyl thiourea. The quantity of bromide ions present is varied from none in example XVll to 94 mole percent in example XXIV. As can be see from table I, a poor image is obtained where no bromide ions are present. Good images, however, are obtained with a wide range of bromide concentrations.

EXAMPLES XXV-XXXI In these examples, the quantities of copper salt, diethyl thiourea and bromide present is maintained constant at 0.3 mole percent copper, 2.4 mole percent diethyl thiourea and 57 mole percent bromide. The quantity of lead salt present is varied from none in example XXV through 1.98 mole percent in example XXXl. As can be seen from table 1, excellent images are obtained with preferred amounts of lead salt.

EXAMPLES XXXll-XXXVII In these examples, the quantities of two ingredients are kept at standard amounts, while the other two are omitted. As shown by table 1, no image or a very faint image is produced in each case.

. EXAMPLES XXXVlll-Llll These examples show variations of image quality where proportions of the four ingredients are varied within a preferred range. As shown by table 1, the images vary from good to excellent in quality.

TABLE I Copper Lead Diethyl Image salt salt thiourea Bromide quality 0. 66 0. 49 50 None. 0. 04 0. 66 0. 49 50 Fair. 0. 09 0. 66 0. 49 50 D0. 0. 15 0. 66 0. 49 50 Good. 0. 21 0. 66 0. 49 50 Do. 0. 29 0. 66 0. 49 59 Fair. 0. 38 0. 66 0. 49 50 D0. 0. 57 0. 66 0. 49 50 D0. 2. 30 0. 66 0. 49 50 Poor. 0. 13 0. 66 0 50 None 0. 13 0. 66 0. 16 50 Fair. 0. 13 0. 66 0. 33 50 Do. 0. 13 0. 66 0. 49 50 Good. 0. 13 0. 66 O. 74 50 D0. 0. 13 0. 66 0. 98 50 D0. 0. 13 0. 66 1. 47 50 Fair. 0. 13 0. 66 0. 49 0 P001. 0. 13 0. 66 0. 49 7. Fair. 0. 13 O. 66 0. 49 15. 0 Do. 0. 13 0. 66 0. 49 22. 5 Good 0. l3 0. 66 0. 49 30. 0 D0. 0. 13 0. 66 0.49 44.0 Do. 0. 13 0. 66 0. 49 56. 0 Do. 0. 13 0. 66 0. 49 94. 0 Poor. 0. 13 0 0. 49 50 None. 0. 13 0. 17 0.49 50 Excellent. 0.13 0.33 0 49 50 Do. 0. 13 0.66 0. 49 50 Good. 0. 13 0. 99 0. 49 50 Fair. 0. 13 1. 32 0. 49 50 D0. 0. 13 1. 98 0. 49 50 None. 0. 13 0. 66 0 0 Do. 0. 13 0 0. 49 0 Do. 0. 13 0 0 50 D0. 0 0. 66 0. 49 0 D0. 0 0. 66 0 50 Do. 0 0 0. 49 50 Do. 0. 17 0.33 U. 59 62 Excellent 9. 0. 33 0. 59 62 Do. 0.17 0.33 0.39 62 Good. 0. 10 0.33 0. 39 62 Do. 0. 17 0. 33 0. 59 50 Do. 0. 10 0. 33 0. 59 50 D0. 0. 13 0. 0. 59 50 Excellent 0. 13 0. 20 0. 59 37 00d. 0. 13 0. 20 0. 88 37 Do. 0. 13 0. 83 0. 59 50 Excellent 0. 13 0.33 0.88 50 Good. 0. 13 0. 33 0. 88 37 Do. 0. 13 0.46 0. 59 50 Excellent. 0. 13 0. 46 0. 88 50 D0. 0. 13 0. 46 0. 59 37 Good. 0.13 0.46 0. 88 37 Do.

In each of the following examples LlV-XC a silver bromide photosensitive emulsion is coated onto a paper base to a dry thickness of about 10 microns. This emulsion is prepared in a conventional manner, such as described in the above-cited publications. The emulsion contains about 2.5 grams of silver per square meter of coated emulsion. The emulsion contains about 0.1 mole percent iodide and at least about 99.0 mole percent bromide in a gelatin matrix. In each of the following examples a layer comprising the described amounts of the sensitizing agents in a gelatin matrix is coated over the photosensitive emulsion to a dry thickness of about 5 microns. In each of the examples, the lead, copper and bromide ions are introduced in the form of lead nitrate, cupric nitrate and potassium bromide. The direct-writing light-developable films thus produced in each example are exposed to an oscillographic trace in a Model 5-124 Recording Oscillograph, available from Consolidated Electrodynamic Corp. The overall, latensification, exposure is to General Electric Cool White Fluorescent lamps. The images produced are then evaluated on a 0 to 10 scale, 0 representing no image and 10 an ideal image. Thus, direct-writing light-developable films containing different amounts of different sensitizers within the overcoating may be compared. The amounts of each sensitizer in mole percent per mole of silver for each sensitizer and the image rating for each example are tabulated in table ll below.

EXAMPLES LIV-LIX in these examples, the quantities of lead salt, bromide and diethyl thiourea are maintained constant at 4 mole percent lead, 2.4 mole percent diethyl thiourea and 57 mole percent bromide. The amount of copper salt present is varied from none in example LIV through 1.8 percent in example LIX. As can be seen from the ratings given for the images produced, as listed in table II, a poor image (rating: 2) is produced with no copper ions present. As copper salt is added, the quality of the image rises to a rating of 10 at 0.3 mole percent copper. As excess copper is added, the image quality falls off rapidly.

EXAMPLES LX-LXV EXAMPLES LXVl-LXXII In each of these examples, the quantities of copper salt, lead salt, and diethyl thiourea are maintained constant at 0.3 mole percent copper, 4 mole percent lead and 2.4 mole percent diethyl thiourea. The quantity of bromide ions present is varied from none in example LXVl to 210 mole percent in example LXXlll. As can be seen from table II, no image is obtained where no bromide ions are present in the overcoating. High-quality images, however, are obtained with a wide range of bromide concentrations.

EXAMPLES LXXlVLXXVIl In these examples, the quantities of copper salt, diethyl thiourea and bromide present is maintained constant at 0.3 mole percent copper, 2.4 mole percent diethyl thiourea and 57 mole percent bromide. The quantity of lead salt present is varied from none in example LXXlV through 8 mole percent in example LXXVll. As can be seen from table ll, excellent images are obtained with varying amounts of lead salt.

EXAMPLES LXXVlll-LXXXlll In these examples, the quantities of two ingredients are kept at standard amounts, while the other two are omitted. As shown by table ll, no image or a very faint image is produced in each case. I

EXAMPLES LXXXIV-LXXXVII In these examples, only one of the four sensitizing ingredients is used in the overcoating. As table II shows, either 7 no image or a very faint image is produced.

EXAMPLE LXXXVlll This example is a control, testing the emulsion with no sensitizing materials. A very faint image results. It should be noted that, as indicated by examples LXXVlll-LXXXII, LXXXVl and LXXXVll the use of less than all four sensitizing ingredients may surprisingly produce a poorer, rather than better, image.

EXAMPLE LXXXIX The overcoating here is identical to that of example LVll. Here, however, the emulsion layer contains silver bromide instead ofsilver iodobromide. The image produced here is of excellent quality, nearly equal to that produced with a silver iodobromide emulsion.

EXAMPLE XC The tested overcoating and emulsion here is the same as in example LVll except that thiourea is used in place of diethyl thiourea. As shown by table ii, an excellent image results, nearly as good as when diethyl thiourea is used.

TABLET? Lead Diethyl salt thiourea Bromide LXXXVIII.

LXXXIX XC As indicated by table II, outstanding traces are obtained on an overcoated silveriodobromide emulsion wherein the overcoating comprises copper salts, lead salts, diethyl thiourea and bromide. Excellent images result where the emulsion contains silver bromide instead of silver iodobromide and where the overcoating contains thiourea instead of diethyl thiourea. By comparing the images obtained without some of the sensitizers with the images produced by including the preferred amounts of these ingredients, one finds an increase in quality which appears to be much greater than additive. Omitting any of the four ingredients results in an image rated 2 or lower. When the preferred amounts of these ingredients are included, the image is rated 10.

If it is desired to compare the ratings shown in table I with the ratings in table II, in general, a table I rating of excellent would have a numerical rating of about 7. Similarly, good, fair and none would have a numerical rating of about 5, 3, and respectively.

Although specific components and proportions have been described in the above examples, other suitable materials, as listed above may be used with similar results. In addition, other materials may be added to the emulsion or to the sensitizing layer to synergize, enhance, or otherwise modify their properties. For example, sensitizing dyes, various finishing aids such as formaldehyde, surface-active agents such as saponin, humectants such as glycerin, stabilizers, matting agents, etc. may be used in either the emulsion or the sensitizing layer.

Other modifications and ramifications of the present invention will occur to those skilled in the art upon a reading of the present disclosure. These are intended to be included within the scope of this invention.

What is claimed is:

1. A photosensitive direct print light-developable material comprising:

1. a photosensitive layer comprising a silver halide and a binder; and

2. coated thereover a layer comprising, based on the silver in said p hotosensitive layer, 7 Mm V v w 7 a. about 0.0? to 1.5 mole percent ofa water-soluble copper salt;

b. about 1 to 50 mole percent of a water-soluble lead salt;

c. about 10 to 200 mole percent of a water-soluble bromide salt; and

d. about 0.4 to 6 mole percent ofa thiourea.

2. The direct print light-developable material of claim 1 wherein said silver halide is silver iodobromide.

3. The direct print light-developable material of claim 1 wherein said thiourea is diethyl thiourea.

4. The direct print light-developable material of claim 1 wherein said overcoated layer comprises, based on the silver in said photosensitive layer,

a. about 0.2 to 0.4 mole percent of a water-soluble copper salt;

b. about 4 to 8 mole percent of a water-soluble lead salt;

c. about 50 to mole percent of a water-soluble bromide salt; and

d. about 1.5 to 3 mole percent ofa thiourea.

5. The direct print light-developable material of claim 4 wherein said thiourea is diethyl thiourea.

6. The direct print light-developable material of claim 1 wherein the thickness of the overcoating is about 0.3 to 0.8 times the thickness of said photosensitive layer.

7. A photosensitive direct print light-developable material comprising: N 7 V A, g

a photosensitive emulsion layer comprising a silver halide and a binder; and based on the silver in said emulsion,

a. about 0.03 to 0.5 mole percent of a water-soluble copper salt;

b. about 0.07 to 2 mole percent of a water-soluble lead salt;

c. about 10 to mole percent of a water-soluble bromide salt; and

d. about 0.2 to 2 mole percent ofa thiourea.

8. The direct print light-developable material of claim 7 wherein said silver halide is silver bromide.

9. The direct print light-developable material of claim 7 wherein said thiourea is diethyl thiourea.

10. The direct print light-developable material of claim 7 wherein said emulsion layer comprises, based on the silver in said emulsion layer,

a. about 0.07 to 0.17 mole percent of a water-soluble copper salt;

b. about 0.13 to 0.66 mole percent of a water-soluble lead salt;

c. about 37 to 62 mole percent ofa water-soluble bromide salt; and,

d. about 0.5 to 1 mole percent ofa thiourea.

11. The direct print light-developable material of claim 10 wherein said thiourea is diethyl thiourea. 

2. coated thereover a layer comprising, based on the silver in said photosensitive layer, a. about 0.03 to 1.5 mole percent of a water-soluble copper salt; b. about 1 to 50 mole percent of a water-soluble lead salt; c. about 10 to 200 mole percent of a water-soluble bromide salt; and d. about 0.4 to 6 mole percent of a thiourea.
 2. The direct print light-developable material of claim 1 wherein said silver halide is silver iodobromide.
 3. The direct print light-developable material of claim 1 wherein said thiourea is diethyl thiourea.
 4. The direct print light-developable material of claim 1 wherein said overcoated layer comprises, based on the silver in said photosensitive layer, a. about 0.2 to 0.4 mole percent of a water-soluble copper salt; b. about 4 to 8 mole percent of a water-soluble lead salt; c. about 50 to 80 mole percent of a water-soluble bromide salt; and d. about 1.5 to 3 mole percent of a thiourea.
 5. The direct print light-developable material of claim 4 wherein said thiourea is diethyl thiourea.
 6. The direct print light-developable material of claim 1 wherein the thickness of the overcoating is about 0.3 to 0.8 times the thickness of said photosensitive layer.
 7. A photosensitive direct print light-developable material comprising: a photosensitive emulsion layer comprising a silver halide and a binder; and based on the silver in said emulsion, a. about 0.03 to 0.5 mole percent of a water-soluble copper salt; b. about 0.07 to 2 mole percent of a water-soluble lead salt; c. about 10 to 150 mole percent of a water-soluble bromide salt; and d. about 0.2 to 2 mole percent of a thiourea.
 8. The direct print light-developable material of claim 7 wherein said silver halide is silver bromide.
 9. The direct print light-developable material of claim 7 wherein said thiourea is diethyl thiourea.
 10. The direct print light-developable material of claim 7 wherein said emulsion layer comprises, based on the silver in said emulsion layer, a. about 0.07 to 0.17 mole percent of a water-soluble copper salt; b. about 0.13 to 0.66 mole percent of a water-soluble lead salt; c. about 37 to 62 mole percent of a water-soluble bromide salt; and, d. about 0.5 to 1 mole percent of a thiourea.
 11. The direct print light-developable material of claim 10 wherein said thiourea is diethyl thiourea. 